1. Field of the Invention
The present invention concerns a gradient coil system and a method for the production of the gradient coil system.
2. Description of the Prior Art
Magnetic resonance technology is a known modality to, among other things, acquire images of the inside of a body of an examination subject. Rapidly-switched gradient fields that are generated by a gradient coil system are superimposed on a static basic magnetic field that is generated by a basic field magnet. The magnetic resonance apparatus also has a radio-frequency system that radiates radio-frequency signals into the examination subject to excite magnetic resonance signals and that acquires the excited magnetic resonance signals, on the basis of which magnetic resonance images are generated.
The gradient coil system is normally formed by multiple coil layers situated one atop the other. The individual coil layers exhibit a complex geometry, are wound in one plane, are mounted atop one another together with insulation layers and are subsequently cast with the gradient coil system under vacuum with a thermosetting casting resin based on epoxy resin. For dissipation of heat, additional layers of coolant tubes or coolant pipes are inserted through which a coolant medium (for example, coolant water) flows in operation. It is also known to introduce additional layers for shim coils into the gradient coil system. In the case of an essentially hollow-cylindrical gradient coil system, the planar finished coil segments are curved into the shape of a cylinder segment and introduced into the gradient coil system. Given the production method described in the preceding, it is particularly disadvantageous (with regard to the later assembly capability) that the individual coil layers are limited in terms of design to an essentially two-dimensional design. A higher production cost also arises for the assembly of approximately nine coil layers with insulation and reinforcement layers belonging thereto. Furthermore, the contacting between the individual coil layers with up to approximately 500 solder points per gradient coil system is very complicated.
An object of the invention is to provide a gradient coil system in which the aforementioned disadvantages are avoided.
The above object is achieved in accordance with the invention by a gradient coil system for a magnetic resonance apparatus at least one part of an electrical conductor arrangement of the gradient coil system is produced by the action of radiation (in particular laser radiation) on a metal powder sinter material.
Compared to the known methods, the following advantages are achieved. In a structural volume available for the gradient coil system, an arbitrary course of the electrical conductors can be selected without consideration of the technical production requirements, thereby allowing previous designs that were considered as unrealizable in terms of production technology to be realized simply. A three-dimensional design plan of the electrical conductor paths of the gradient coil system can be directly adopted for the production method. Each change of the path of the electrical conductors can be done without adaptation of the production means, so that (among other things) a time savings is achieved in the development phase. Contactings of individual conductors among one another are no longer necessary at all given the finished sintered conductor arrangement. The manual assembly effort is drastically reduced. Since no residual stresses arise (for example due to a curvature or coiling) that can cause deformations in the sealing process, a higher precision is achieved.